1. Field of the Invention
The present invention relates to an improved method and apparatus for mounting and demounting a pneumatic tire from a single-piece dual-flanged rim, and more particularly to a method and apparatus employed for mounting giant tires commonly referred to as "off-highway tires" used on large earth moving and mining equipment.
2. Prior Art
The general practice in the industry heretofore has been to mount very large pneumatic tires onto five piece rims which have locking rings and gasket rings. The process of mounting off-highway tires onto these five piece rims is generally slow requiring several safety precautions to avoid serious injuries. The industry concluded that a single-piece rim, such as the kind used on automobiles and the like, would be more desirable; since the mounting of the tire onto the single-piece rim is generally safer. However, various problems occured when using crow bars and other prying tools to mount the giant tires onto these new single-piece rims. The beads of the giant tires are reinforced with heavy wire thereby requiring a substantial force to be applied in order to draw the beads out of round which oftentimes causes subsequent damage to the adjacent rubber and cord material.
A prior art patent, U.S. Pat. No. 3,489,998 to Malinski, discloses a method and apparatus for mounting and demounting giant tires onto the single-piece rims incorporating a hydraulic pusher and bead deflector guide arms to manipulate the tire onto the rim. Even with the use of the aforementioned patent or the other devices designed to mount off-highway tires onto single-pieced rims, problems involving damage to the bead and the rubber have still been encountered. No prior art device uses an oblique mounting cone in conjunction with a sequential mounting procedure designed to gently press the tires onto the rim thereby minimizing costly damage to the tire.